Battery pack and vehicle comprising the battery pack

ABSTRACT

The disclosure relates to the technical field of traction batteries, and in particular to a battery pack and a vehicle comprising the battery pack. The invention aims at the problem of large heat loss in the existing traction battery in a low-temperature environment. To this end, the battery pack of the disclosure comprises: a frame internally formed with an installation site; a battery module mounted in the installation site and comprising a number of cells; and a side beam connected to an outer side wall of the frame and made of a first thermal insulation material. The above arrangement can reduce the heat transfer coefficient of natural convection between the side wall of the frame and the environment, and reduce the heat flux, thereby reducing the temperature loss of the cells.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of China Patent Application No.202011454326.3 filed Dec. 10, 2020, the entire contents of which areincorporated herein by reference.

TECHNICAL FIELD

The disclosure relates to the technical field of traction batteries, andin particular to a battery pack and a vehicle comprising the batterypack.

BACKGROUND ART

With the increase in the market share of new energy vehicles, especiallybattery electric vehicles, the use of battery electric vehicles in thecold northern environment is becoming more and more popular. When avehicle is left to stand for a long time in a cold environment, whetherthe internal cell temperature of a traction battery, which is a corecomponent of an electric vehicle, can be maintained in an idealtemperature range will directly affect the chemical activity and servicelife of the traction battery.

Generally, in order to ensure the overall structural strength of thetraction battery, an outer casing of the traction battery is made of ametal material, in this way, however, in a low-temperature environment,it is easier for the metal material to exchange heat with the externalenvironment, which causes the cell temperature to drop too quickly. Inorder to solve the above-mentioned problems, some manufacturers haveprovided traction batteries with an active heating function. When thebattery temperature drops to a certain threshold, the traction batteryis actively heated. However, this method requires frequent or long-termactivation of the heater to keep the battery warm, which is not onlyinefficient, but also consumes a lot of power from the traction batteryand sacrifices a lot of cruising range.

Accordingly, there is a need in the art for a new battery pack and avehicle comprising the battery pack to solve the above-mentionedproblems.

SUMMARY OF THE INVENTION

In order to solve at least one of the above problems in the prior art,that is, to solve the problem of large heat loss of the existingtraction battery in a low-temperature environment, the disclosureprovides a battery pack comprising: a frame internally formed with aninstallation site; a battery module mounted in the installation site andthe battery module comprises a number of cells; and a side beamconnected to an outer side wall of the frame and made of a first thermalinsulation material.

In a preferred technical solution of the battery pack as describedabove, the first thermal insulation material is a microcellular expandedcomposite material.

In a preferred technical solution of the battery pack as describedabove, the microcellular expanded composite material is microcellularexpanded polypropylene or microcellular expanded nylon.

In a preferred technical solution of the battery pack as describedabove, there are two side beams, which are connected to two side wallsof the frame respectively in a length direction of the frame.

In a preferred technical solution of the battery pack as describedabove, the interior of the side beam is filled with an energy-absorbingmaterial.

In a preferred technical solution of the battery pack as describedabove, the interior of the side beam is formed with a plurality of ribplates, which divide the interior of the side beam into a plurality ofinstallation chambers opening toward the frame, and the energy-absorbingmaterial is filled in the plurality of installation chambers.

In a preferred technical solution of the battery pack as describedabove, the energy-absorbing material is expanded polypropylene orethylene-vinyl acetate copolymer.

In a preferred technical solution of the battery pack as describedabove, the outer side wall of the frame is provided with a lug forconnecting to a vehicle, the interior of the side beam is formed with anenveloping chamber opening toward the frame, and the lug is accommodatedin the enveloping chamber in a connected state.

In a preferred technical solution of the battery pack as describedabove, the outer side wall of the frame is formed with a plurality ofreinforcing ribs, a plurality of filling spaces are formed between theplurality of reinforcing ribs, and each of the filling space is filledwith a second thermal insulation material.

In a preferred technical solution of the battery pack as describedabove, the second thermal insulation material is an expanded thermalinsulation material.

In a preferred technical solution of the battery pack as describedabove, the expanded thermal insulation material is silicone foam,polyurethane sponge or polyvinyl chloride expanded plastic.

In a preferred technical solution of the battery pack as describedabove, the frame is a hollow structure and is formed with a cavity, andthe cavity is filled with a phase-change material.

In a preferred technical solution of the battery pack as describedabove, the phase-change material is an inorganic phase-change material,an organic phase-change material or a composite phase-change material.

In a preferred technical solution of the battery pack as describedabove, the battery pack further comprises an active thermal compensationassembly, which is provided on a heat dissipation path of the batterymodule and is configured to be able to heat the cells.

In a preferred technical solution of the battery pack as describedabove, the active thermal compensation assembly is connected to abattery management system.

In a preferred technical solution of the battery pack as describedabove, the frame comprises an outer frame and an inner frame, theplurality of installation sites are formed in an enclosed manner betweenthe outer frame and the inner frame, and the active thermal compensationassembly is provided on an inner side wall of the outer frame.

In a preferred technical solution of the battery pack as describedabove, the active thermal compensation assembly is an electric heater, agraphene heat radiation sheet or a thermoelectric cooler.

In a preferred technical solution of the battery pack as describedabove, the battery pack further comprises a temperature equalizingassembly, which is arranged in the frame and is configured to be able tobalance the temperature between different cells.

In a preferred technical solution of the battery pack as describedabove, the temperature equalizing assembly is attached to the outer sidewall of the battery module close to an outer periphery of the frame.

In a preferred technical solution of the battery pack as describedabove, the temperature equalizing assembly is a heat pipe group, athermal conductive aluminum plate group or a thermal conductive siliconpad group.

The present application further provides a vehicle comprising a batterypack according to any one of the above preferable technical solutions.

It can be understood by those skilled in the art that in a preferredtechnical solution of the disclosure, a battery pack comprises: a frameinternally formed with an installation site; a battery module mounted inthe installation site and comprising a number of cells; and a side beamconnected to an outer side wall of the frame and made of a first thermalinsulation material.

The above arrangement can reduce the heat transfer coefficient ofnatural convection between the side wall of the frame and theenvironment, and reduce the heat flux, thereby reducing the temperatureloss of the cells. Specifically, the side beam is connected to the outerside wall of the frame and the side beam is made of the first thermalinsulation material, such that the side beam and the frame can performheat exchange at a lower heat transfer rate during normal use of thebattery pack. That is, in low-temperature conditions, the speed of heattransferred to the side beam through the connection between the frameand the side beam can be reduced, and the speed of heat transfer andheat radiation from the side beam to the outside air is also reduced. Asa result, loss of heat is reduced, and the temperature of the cells ismaintained at a rational value for a long time, and the performance ofthe battery pack in the low-temperature conditions is ensured.

Further, the interior of the side beam is filled with theenergy-absorbing material, such that when the vehicle collides, part ofthe energy generated by the collision can be absorbed by theenergy-absorbing material in the side beam, thereby reducing the impactof the collision on the battery pack and improving the safety of thebattery pack.

Further, the enveloping chamber is formed in the side beam, and theenveloping chamber envelops the lug provided on the outer side wall ofthe frame, so that the heat loss through the lug can be further reduced.

Further, the plurality of reinforcing ribs are formed on the outer sidewall of the frame, the filling spaces are formed between the reinforcingribs, and the filling spaces are then filled with the second thermalinsulation material, such that the reinforcing ribs have the function ofincreasing the structural strength, and the filling space formed betweenthe reinforcing ribs can also exert sufficient heat loss preventionability through the filled expanded thermal insulation material.Therefore, when the battery pack is left to stand in a cold environment,the heat flux around the frame is significantly reduced, and thetemperature of the cells is significantly increased compared to aconventionally designed battery pack.

Further, the hollow structure of the frame is filled with thephase-change material, such that when the temperature of the cellsdecreases to a certain level, the phase-change material works andreleases latent heat, which slows the rate of heat dissipation from thebattery to the outside and prolongs the heat preservation time.

Further, the active thermal compensation assembly is provided on theheat dissipation path of the battery module, such that when thetemperature of the cells decreases, only a small amount of heat sourceneeds to be applied to a specific heat transfer path to compensate forthe heat lost to the air, thereby prolonging the heat preservation timeof the cells. Compared with the heating function of the existing batterypack, this arrangement can reduce battery power consumption and reducethe impact of active thermal compensation on the cruising range.

Further, the temperature equalizing assembly is provided in the frame,and a heat transfer channel can be created between a cell with a highertemperature and a cell with a lower temperature inside the battery pack,such that the temperature difference between the cells in the batterypack is reduced, the temperature uniformity of the battery pack isimproved, and the shortest stave effect is alleviated.

Another aspect of the disclosure also provides a vehicle, and theabove-mentioned battery pack is mounted on the vehicle, such that whenthe vehicle is left to stand in a cold environment, the battery pack canbe kept warm for a long enough time with little power consumption oreven without consuming its own power, ensuring that the performance ofthe battery pack will not be affected after being placed outdoors for along time.

Solution 1: A battery pack, comprising:a frame internally formed with an installation site;a battery module mounted in the installation site and comprising anumber of cells; anda side beam connected to an outer side wall of the frame and made of afirst thermal insulation material.Solution 2: the battery pack according to Solution 1, wherein the firstthermal insulation material is a microcellular expanded compositematerial.Solution 3: the battery pack according to Solution 2, wherein themicrocellular expanded composite material is microcellular expandedpolypropylene or microcellular expanded nylon.Solution 4: the battery pack according to Solution 1, wherein there aretwo side beams, which are connected to two side walls of the framerespectively in a length direction of the frame.Solution 5: the battery pack according to Solution 1, wherein theinterior of the side beam is filled with an energy-absorbing material.Solution 6: the battery pack according to Solution 5, wherein theinterior of the side beam is formed with a plurality of rib plates,which divide the interior of the side beam into a plurality ofinstallation chambers opening toward the frame, and the energy-absorbingmaterial is filled in the plurality of installation chambers.Solution 7: the battery pack according to Solution 5, wherein theenergy-absorbing material is expanded polypropylene or ethylene-vinylacetate copolymer.Solution 8: the battery pack according to Solution 1, wherein the outerside wall of the frame is provided with a lug for connecting to avehicle, the interior of the side beam is formed with an envelopingchamber opening toward the frame, and the lug is accommodated in theenveloping chamber in a connected state.Solution 9: the battery pack according to Solution 1, wherein the outerside wall of the frame is formed with a plurality of reinforcing ribs, aplurality of filling spaces are formed between the plurality ofreinforcing ribs, and each of the filling space is filled with a secondthermal insulation material.Solution 10: the battery pack according to Solution 9, wherein thesecond thermal insulation material is an expanded thermal insulationmaterial.Solution 11: the battery pack according to Solution 10, wherein theexpanded thermal insulation material is silicone foam, polyurethanesponge or polyvinyl chloride expanded plastic.Solution 12: the battery pack according to Solution 1, wherein the frameis a hollow structure and is formed with a cavity, and the cavity isfilled with a phase-change material.Solution 13: the battery pack according to Solution 12, wherein thephase-change material is an inorganic phase-change material, an organicphase-change material or a composite phase-change material.Solution 14: the battery pack according to Solution 1, wherein thebattery pack further comprises an active thermal compensation assembly,which is provided on a heat dissipation path of the battery module andis configured to be able to heat the cells.Solution 15: the battery pack according to Solution 14, wherein theactive thermal compensation assembly is connected to a batterymanagement system.Solution 16: the battery pack according to Solution 14, wherein theframe comprises an outer frame and an inner frame, the plurality ofinstallation sites are formed in an enclosed manner between the outerframe and the inner frame, and the active thermal compensation assemblyis provided on an inner side wall of the outer frame.Solution 17: the battery pack according to Solution 14, wherein theactive thermal compensation assembly is an electric heater, a grapheneheat radiation sheet or a thermoelectric cooler.Solution 18: the battery pack according to Solution 1, wherein thebattery pack further comprises a temperature equalizing assembly, whichis arranged in the frame and is configured to be able to balance thetemperature between different cells.Solution 19: the battery pack according to Solution 18, wherein thetemperature equalizing assembly is attached to the outer side wall ofthe battery module close to an outer periphery of the frame.Solution 20: the battery pack according to Solution 18, wherein thetemperature equalizing assembly is a heat pipe group, an aluminum plategroup or a thermal conductive silicon pad group.Solution 21: a vehicle, comprising a battery pack according to any oneof Solutions 1 to 20.

BRIEF DESCRIPTION OF THE DRAWINGS

The battery pack of the disclosure and the vehicle comprising thebattery pack will be described below with reference to the drawings andin conjunction with a battery electric vehicle. In the accompanyingdrawings:

FIG. 1 is an exploded view of a battery pack of the disclosure;

FIG. 2 is a partial sectional view of the battery pack of thedisclosure;

FIG. 3 is a structural diagram of a side beam of the battery pack of thedisclosure;

FIG. 4 is a sectional view of the side beam of the battery pack of thedisclosure;

FIG. 5 is a sectional view of a first embodiment of an outer frame ofthe disclosure;

FIG. 6 is a diagram of an installation position of a temperatureequalizing assembly in a battery module of the disclosure; and

FIG. 7 is a sectional view of a second embodiment of an outer frame ofthe disclosure.

LIST OF REFERENCE NUMERALS

1: Frame; 11: Outer frame; 12: Inner frame; 13: Installation site; 14:Lug; 15: Reinforcing rib; 16: Filling space; 17: Cavity; 2: Batterymodule; 21: Cell; 3: Side beam; 31: Rib plate; 32: Installation chamber;33: Enveloping chamber; 34: Through hole; 4: Second thermal insulationmaterial; 5: Energy-absorbing material; 6: Phase-change material; 7:Thermal compensation assembly; 8: Temperature equalizing assembly.

DETAILED DESCRIPTION OF EMBODIMENTS

Preferred embodiments of the disclosure are described below withreference to the drawings. It should be understood by those skilled inthe art that these embodiments are only for explaining the technicalprinciples of the disclosure and are not intended to limit the scope ofprotection of the disclosure. For example, although this embodiment isdescribed in conjunction with a battery electric vehicle, it is notintended to limit the scope of protection of the disclosure. Withoutdeparting from the principles of the disclosure, those skilled in theart can apply the battery pack of the disclosure to other applicationscenarios. For example, the battery pack of the disclosure may also beapplied to hybrid vehicles, electric bicycles, electric motorcycles, andso on.

It should be noted that in the description of the disclosure, the terms,such as “center”, “upper”, “lower”, “left”, “right”, “vertical”,“horizontal”, “inner” and “outer”, that indicate directions orpositional relationships are based on the directions or positionalrelationships shown in the drawings only for convenience of description,and do not indicate or imply that the device or element must have aspecific orientation, be constructed and operated in a specificorientation, and therefore cannot be understood as limitation to thedisclosure. In addition, the terms “first”, “second” and “third” are fordescriptive purposes only and should not be construed as indicating orimplying relative importance.

In addition, it should also be noted that, in the description of thedisclosure, the terms “mount”, “engage” and “connect” should beinterpreted in a broad sense unless explicitly defined and limitedotherwise, which, for example, may mean a fixed connection, a detachableconnection or an integral connection; may mean a mechanical connectionor an electrical connection; and may mean a direct connection, anindirect connection by means of an intermediary, or internalcommunication between two elements. For those skilled in the art, thespecific meaning of the above-mentioned terms in the disclosure can beinterpreted according to the specific situation.

First, referring to FIG. 1, a first embodiment of a battery pack of thedisclosure will be described. FIG. 1 is an exploded view of the batterypack of the disclosure.

As shown in FIG. 1, in order to solve the problem of large heat loss ofexisting traction batteries in a low-temperature environment, thedisclosure provides a battery pack comprising a frame 1, a number ofbattery modules 2 and two side beams 3. A number of installation sites13 are formed in the frame 1, and each battery module 2 is installed inone of the installation sites 13. Each battery module 2 comprises aplurality of cells 21(see FIG. 6), and the plurality of cells 21 areconnected in series and/or in parallel. The two side beams 3 areconnected to two outer side walls of the frame 1 respectively, and theside beams 3 are made of a first thermal insulation material.

The above arrangement can reduce the heat transfer coefficient ofnatural convection between the side walls of the frame 1 and theenvironment, and reduce the heat flux, thereby reducing the temperatureloss of the cells 21. Specifically, the side beams 3 are connected tothe outer side walls of the frame 1 and the side beams 3 are made of thefirst thermal insulation material, such that the side beams 3 and theframe 1 can perform heat exchange at a lower heat transfer rate duringnormal use of the battery pack. That is, in low-temperature conditions,the speed of heat transferred to the side beam 3 through the connectionbetween the frame 1 and the side beam 3 can be reduced, and the speed ofheat transfer and heat radiation from the side beam 3 to the outside airis also reduced. As a result, loss of heat is reduced, and thetemperature of the cells 21 is maintained at a rational value for a longtime, and the performance of the battery pack in the low-temperatureconditions is ensured.

It can be understood by those skilled in the art that, although theabove embodiment only introduces that the battery pack comprises theframe 1, the battery module 2 and the side beams 3, it is obvious thatthey are not all the components of the battery pack. Generally, thebattery pack may further comprise one or more of a housing, an uppercover plate, a lower cover plate, a cooling plate, a battery managementsystem (BMS), etc., and these structures are not shown in the drawingsin order to unnecessarily obscure the examples of the presentdisclosure.

Hereinafter, further referring to FIGS. 1 to 6, the battery pack of thisembodiment will be described in detail. In the figures, FIG. 2 is apartial sectional view of the battery pack of the disclosure; FIG. 3 isa structural diagram of the side beam of the battery pack of thedisclosure; FIG. 4 is a sectional view of the side beam of the batterypack of the disclosure; FIG. 5 is a sectional view of a first embodimentof an outer frame of the disclosure; and FIG. 6 is a diagram of aninstallation position of a temperature equalizing assembly in thebattery module of the disclosure.

As shown in FIG. 1, in a possible embodiment, the frame 1 is made of ametal material, for example is cast from an aluminum alloy or stainlesssteel. The frame comprises an outer frame 11 and inner frame 12, theouter frame 11 generally has a “convex” shape, and six rectangularinstallation sites 13 are formed between the outer frame 11 and theinner frame 12. Accordingly, there are six battery modules 2, the outerperiphery of the battery modules 2 is shaped to adapt to theinstallation sites 13, and each battery module 2 is fixedly embedded inone of the installation sites 13. The outer side wall of the outer frame11 is integrally formed with a plurality of lugs 14, and each lug 14 isprovided with a connection hole. After the battery pack is assembled,the lugs 14 can be fixedly connected to a chassis of the batteryelectric vehicle (or hereinafter called electric vehicle or vehicle)through a connectors such as screws and pins, so that the battery packis fixed on the battery electric vehicle and provides the vehicle withenergy.

Still referring to FIG. 1, in this embodiment, there are two side beams3, and the two side beams 3 are connected to two side walls of the outerframe 11 respectively in a length direction of the frame 1 (i.e. thedirection A in FIG. 1). Specifically, referring to FIGS. 2 to 4, theside beam 3 is in the shape of a long strip as a whole, and is connectedto the outer frame 11 by means of riveting. The side beam 3 as a wholeis integrally molded from a first thermal insulation material, which ispreferably a microcellular expanded composite material, such as amicrocellular expanded polypropylene material. After being molded, theside of the side beam 3 facing the outer frame 11 is an opening side,and a plurality of rib plates 31 are formed in the opening. Theplurality of rib plates 31 divide the inside of the side beam 3 to aplurality of installation chambers 32, and each installation chamber 32is filled with an energy-absorbing material 5. The energy-absorbingmaterial 5 is preferably expanded polypropylene (EPP). An envelopingchamber 33 is also formed inside the opening. In a riveted state, thelug 14 is accommodated in the enveloping chamber 33. The side beam 3 isprovided with a through hole 34 at the position corresponding to theconnection hole in the lug 14, so that the connector can pass throughthe through hole 34 and fix the lug 14 to the chassis of the vehicle.

Referring to FIGS. 1, 2 and 5, the outer side wall of the outer frame 11is formed with a plurality of horizontal and vertical reinforcing ribs15, a plurality of filling spaces 16 are formed between the plurality ofreinforcing ribs 15, and each filling space 16 is filled with a secondthermal insulation material 4. The second thermal insulation material 4is preferably an expanded thermal insulation material, such as siliconefoam, polyurethane sponge (also called PU foam) or polyvinyl chlorideexpanded plastic (also called expanded PVC). The depth and the surfacearea of the filling space 16 are calculated such that the filled thermalinsulation material can exert sufficient thermal insulation ability.Since the frame 1 itself has the requirements for load-bearingmechanical properties and at the same time needs to have the ability toinsulate and preserve heat, the larger the filling space 16 means themore second thermal insulation materials 4 that can be filled, thebetter the heat preservation performance, and therefore the worse thestructural performance. Therefore, the way in which the filling space 16is calculated should be to maximize the filling space 16 while ensuringthe structural strength. As an example, three parameters, namely thebottom surface area of the filling space 16, the thickness of thereinforcing ribs 15, and the thickness of a base material of the outerframe 11, are taken and are simulated sequentially through an orthogonalanalysis method. On the basis of qualified simulation of the mechanicalstructure performance, simulation of heat preservation and heatdissipation is carried out. The parameter configuration with the bestheat preservation performance is the best solution.

Continuing to refer to FIGS. 1 and 2, the battery pack further comprisesan active thermal compensation assembly 7, the active thermalcompensation assembly 7 is provided on a heat dissipation path of thebattery module 2, and the active thermal compensation assembly 7 isconfigured to be able to heat the cells 21. Specifically, the activethermal compensation assembly 7 may be an electric heater (such as aresistance heater, an electromagnetic heater, a short-wave heater,etc.), or may be a graphene heat radiation sheet, or may be anelectrical element utilizing the Peltier effect, such as athermoelectric cooler. The arrangement position of the active thermalcompensation assembly 7 is determined based on quantitative analysis ofa heat transfer path. As an example, based on thermal simulation heatdissipation model, a heat transfer interface of each assembly (such asthe environment and the housing, the cooling plate and the frame 1, theupper cover and housing, the cell 21 and glue, etc.) is extracted tobuild a thermal simulation model to calculate the heat flux of eachassembly in several hours, and then based on the above-mentionedcalculation data, a data analysis model is established to find out aheat transfer sensitive path, that is, one or more optimal arrangementpositions of the active thermal compensation assembly 7 are determined.In this embodiment, as shown in FIG. 1, two inner side walls of theouter frame 11 in the length direction are taken as the optimalarrangement positions, and the active thermal compensation assembly 7 isattached to the inner side wall or is embedded in the inner side wall.

In addition, in a possible application scenario, the active thermalcompensation assembly 7 is connected to a battery management system(BMS), and is controlled by the battery management system. When thetemperature of the cells 21 drops to a certain temperature threshold,the battery management system determines optimal working time and powerof the active thermal compensation assembly 7 (that is, power andworking time of the assembly) according to the state of the cells 21 anda standing time of the battery pack, and then controls, according to theabove-mentioned parameters, the actuation of the active thermalcompensation assembly 7 to heat the cells 21. The power of activethermal compensation should be determined based on a heat preservationtarget (for example, after heat preservation for 12 h, the temperatureis higher than or equal to 0° C.). The determination method may beroughly determining multiple sets of power and working time parametersbased on the heat capacity of the cells 21, the temperature thresholdand the heat preservation target, and then multiple sets of parametersare taken to respectively undergo thermal simulation, finally the mostenergy-saving power and working time under the heat preservation targetare determined.

Referring to FIGS. 1, 2 and 6, the battery pack further comprises atemperature equalizing assembly 8, the temperature equalizing assembly 8is arranged in the frame 1, and the temperature equalizing assembly 8 isconfigured to be able to balance the temperature between different cells21. Specifically, the temperature equalizing assembly 8 preferably usesheat pipe groups, each heat pipe group comprises a plurality of heatpipes, and the heat pipe groups are attached to outer side walls of someof the battery modules 2 close to the outer frame 11. As an example, asshown in FIG. 1, two heat pipe groups respectively attached to the outerside walls of two battery modules 2 arranged in the length direction ofthe frame 1 and close to a long-side outer side wall of the outer frame11, and the length of each heat pipe group is substantially equal tothat of the side wall of the battery module 2.

The above arrangement has the following advantages:

The frame 1 is made of a metal material, and the plurality ofreinforcing ribs 15 are provided on the outer side wall of the frame 1,and the filling spaces 16 are formed between the reinforcing ribs 15.The filling space 16 is filled with an expanded thermal insulationmaterial, and then the side beam 3 is made of a microcellular expandedcomposite material. The installation chamber 32 and the envelopingchamber 33 are formed in the side beam 3, and the installation chamber32 is filled with the energy-absorbing material 5. The envelopingchamber 33 envelops the lug 14, and the battery pack of this applicationcan take into account both the effects of structural strength andthermal insulation.

First of all, the provision of the reinforcing ribs 15 has the effect ofincreasing the structural strength, and the filling spaces 16 formedbetween the reinforcing ribs 15 can also exert sufficient heat lossprevention ability through the filled expanded thermal insulationmaterial. Therefore, when the battery pack is left to stand in a coldenvironment, the heat flux around the frame 1 is significantly reduced,and the temperature of the cells 21 is significantly increased comparedto a conventionally designed battery pack. Secondly, the side beam 3 ismade of the microcellular expanded composite material, such that theside beam 3 and the frame 1 perform heat exchange at a lower heattransfer rate. That is, in low-temperature conditions, the speed of heattransferred to the side beam 3 through the connection between the frame1 and the side beam 3 can be reduced, and the speed of heat transfer andheat radiation from the side beam 3 to the outside air is also reduced.As a result, loss of heat is reduced, and the temperature of the cells21 is maintained at a rational value for a long time, and theperformance of the battery pack in the low-temperature conditions isensured. Next, the interior of the side beam 3 is filled with theexpanded polypropylene (EPP), such that when the vehicle collides, partof the energy generated by the collision can be absorbed by the expandedpolypropylene in the side beam 3, thereby reducing the impact of thecollision on the battery pack and improving the safety of the batterypack. Finally, the enveloping chamber 33 is formed in the side beam 3,and the enveloping chamber 33 envelops the lug 14 provided on the outerside wall of the frame 1, such that the heat loss through the lug 14 canalso be reduced, and the heat loss of the battery pack can be furtherreduced.

Further, the cooling of the battery pack presents a specific temperaturedistribution trend, such as being cold at the periphery and hot in themiddle, and therefore, the cells 21 at the periphery become the“shortest stave” that limits the performance of the entire vehicle. Inthis application, by attaching the heat pipe group between the outerside wall of the battery module 2 and the outer frame 11, a heattransfer channel can be created between a cell 21 with a highertemperature and a cell 21 with a lower temperature inside the batterypack. The heat from the cell 21 in the middle is transferred to thecells 21 at the periphery in a timely manner, such that the temperaturedifference between the cells 21 in the battery pack is reduced, thetemperature uniformity of the battery pack is improved, and the shorteststave effect is alleviated.

Further, the active thermal compensation assembly 7 is provided on theheat dissipation path of the battery module 2, and the active thermalcompensation assembly 7 is provided on the heat transfer sensitive path,such that when the temperature of the cells 21 decreases, only a smallamount of heat source needs to be applied to a specific heat transferpath to compensate for the heat lost to the air, thereby prolonging theheat preservation time of the cells 21. Compared with the heatingfunction of the existing battery pack, this arrangement can reducebattery power consumption and reduce the impact of active thermalcompensation on the cruising range. In particular, when heatpreservation methods such as the active thermal compensation assembly 7and the outer side wall of the frame 1 being filled with the expandedthermal insulation material, the side beam 3 being made of themicrocellular expanded composite material, the interior of the side beambeing filled with the expanded polypropylene, the side beam 3 envelopingthe lug 14, and heat pipes being attached to the outer side wall of thebattery module 2 are used in combination, the battery energy consumptioncan be significantly reduced and the heating effect can be improved.

Hereinafter, referring to FIG. 7, a second embodiment of the disclosurewill be briefly introduced. FIG. 7 is a sectional view of a secondembodiment of an outer frame of the disclosure.

As shown in FIG. 7, the frame 1 is arranged as follows: The frame 1 isconfigured as a hollow structure and is formed with a cavity 17, and thecavity 17 is filled with a phase-change material 6. The frame 1 may be acasting or a profiled part, in the interior of which a closed orsemi-closed cavity 17 is reserved as a space for being filled with thephase-change material 6. The phase-change material 6 may utilize aninorganic phase-change material (such as crystal hydrated salt, moltensalt, and metal alloy), an organic phase-change material (such asparaffin, carboxylic acid, ester, and polyol) or a compositephase-change material (such as a mixture of an organic phase-changematerial and an inorganic phase-change material). The phase-changematerial 6 is a material having a specific phase-change latent heat anda phase-change temperature point obtained by calculation.

The characteristics of the phase-change material 6 include thephase-change latent heat and the temperature phase-change point. Amongthese two parameters, the phase-change temperature in particular iscustomized according to requirements. The placement area and amount ofthe phase-change material 6 may be obtained based on thermal simulationof the battery. By way of example, simulation software may be used tocalculate the energy Q required to delay the time in which thetemperature of a specific area in the battery pack decreases from 5° C.to 0° C. by a hours, and then based on the calculation result, thematerial with a phase-change temperature of about 5° C. and aphase-change latent heat greater than Q is selected as a qualifiedsolution. In this way, when the temperature of the specific area in thebattery pack drops to about 5° C., the phase-change material 6 works andreleases latent heat.

The hollow structure of the frame 1 is filled with the phase-changematerial 6, such that when the temperature of the cells 21 decreases toa certain level, the phase-change material 6 works and releases latentheat, which slows the rate of heat dissipation from the battery to theoutside and prolongs the heat preservation time.

It should be noted that although only two examples are provided for thebattery pack here, this is not intended to limit the scope of protectionof the disclosure. Those skilled in the art can adjust the abovearrangements without deviating from the principle of the disclosure, sothat the disclosure can be applied to more specific applicationscenarios.

As an example, in an alternative embodiment, although the first thermalinsulation material is introduced in the form of the microcellularexpanded composite material, such a thermal insulation material is notinvariable. Under the condition that the strength and thermal insulationeffect can be satisfied, those skilled in the art may also utilizeanother thermal insulation material for replacement. As an example, thefirst thermal insulation material may also be a material made through asupercritical extraction process, such as a composite material formed bya combination of one or more of aerogel, glass fiber, and polyester.Similarly, in addition to the microcellular expanded polypropyleneintroduced in the above embodiments, the microcellular expandedcomposite material may be a microcellular expanded nylon material, etc.

Likewise, the second thermal insulation material 4 may also be adjustedin other embodiments. For example, the second thermal insulationmaterial may also be a material made through a supercritical extractionprocess, such as a composite material formed by a combination of one ormore of aerogel, glass fiber, and polyester.

Likewise, the energy-absorbing material 5 may be adjusted in otherembodiments. For example, the energy-absorbing material 5 may also beethylene-vinyl acetate copolymer (EVA), etc.

As another example, in another alternative embodiment, although theabove-mentioned temperature equalizing assembly is introduced withreference to the heat pipe group, this is not restrictive. In otherembodiments, a thermal conductive aluminum plate group or a thermalconductive silicon pad group may also be used for replacement, and thisreplacement does not deviate from the principle of this application.

In other alternative embodiments, those skilled in the art can deletesome of the features on the basis of this, in order to obtain technicalsolutions that meet other application scenarios by combining thefeatures. As an example, those skilled in the art may omit one or morefeatures of the rib plates 31, the lug 14, the reinforcing ribs 15, theenergy-absorbing material 5, the second thermal insulation material 4,the active thermal compensation assembly 7 and the temperatureequalizing assembly 8.

As another example, in an alternative embodiment, although the side beam3 is connected to the outer frame 11 by means of riveting, thisconnection method is not unique. In other embodiments, the side beam 3may also be fixedly connected to the outer frame 11 by means of welding,screwing, etc.

As another example, in another alternative embodiment, although thearrangement position and the number of each feature have been limitedthe above technical solutions, such an arrangement is not unique, andthose skilled in the art may adjust the number and arrangement positionthereof such that the adjusted technical solutions can be applied tomore specific application scenarios. As an example, in addition to thesix installation sites 13 for the battery modules 2, the outer frame 11and the inner frame 12 may form any number of installation sites 13,such as one, two, three, or seven, as long as the number of the batterymodules 2 is accordingly adjusted. As another example, the side beam 3may be arranged around all the outer side walls of the frame 1, and mayalso be arranged at one outer side wall. As yet another example, theactive thermal compensation assembly 7 may be attached to one or more ofthe four inner side walls of the outer frame 11, and may also beattached to the side wall of the inner frame 12. As still anotherexample, the temperature equalizing assembly 8 may be arranged aroundthe outer peripheral sides of all the battery modules 2 arranged facingthe outer frame 11, and may also be arranged only on the outer side wallof some battery modules 2.

Of course, the above alternative embodiments, or the alternativeembodiments and the preferable embodiments may be cross-usedcooperatively, so as to obtain new embodiments that are suitable formore specific application scenarios by combining the above embodiments.

The disclosure further provides a vehicle, on which the battery packdescribed above is mounted. The vehicle is preferably a battery electricvehicle, and the battery pack is fixedly connected to a chassis of thevehicle.

The above-mentioned battery pack is mounted on the vehicle, such thatwhen the vehicle is left to stand in a cold environment, the batterypack can be kept warm for a long enough time with little powerconsumption or even without consuming its own power, ensuring that theperformance of the battery pack will not be affected after being placedoutdoors for a long time. After repeated experiments, observations,analysis and comparisons, the inventors have found that when theelectric vehicle equipped with the battery pack of this application isleft to stand in a cold environment, the battery can be kept warm for along enough (overnight) time without consuming its own power, ensuringthat the performance (endurance/acceleration/maximum speed, etc.) of thecar will not be affected after being left outdoors all night. Moreover,when the electric vehicle equipped with the battery pack of thisapplication is left to stand in a cold environment for a long time (>1day), the active thermal compensation assembly 7 can be actuated to slowdown the heat loss of the battery, ensuring that the vehicle still hassufficient vehicle performance after being left to stand for a longertime.

Those skilled in the art should understand that although some examplesas described herein comprise certain features included in otherexamples, instead of other features, the combination of the features ofdifferent examples means to be within the scope of the disclosure andform a different example. For example, in the claims of the disclosure,any one of the examples set forth thereby can be used in anycombination.

Heretofore, the technical solutions of the disclosure have beendescribed in conjunction with the preferred embodiments shown in thedrawings, however, those skilled in the art can readily understand thatthe scope of protection of the disclosure is obviously not limited tothese specific embodiments. Those skilled in the art could makeequivalent changes or substitutions to the related technical featureswithout departing from the principles of the disclosure, and all thetechnical solutions after the changes or the substitutions fall withinthe scope of protection of the disclosure.

1. A battery pack, comprising: a frame internally formed with aninstallation site; a battery module mounted in the installation site,and the battery module comprises a number of cells; and a side beamconnected to an outer side wall of the frame and made of a first thermalinsulation material.
 2. The battery pack according to claim 1, whereinthe first thermal insulation material is a microcellular expandedcomposite material.
 3. The battery pack according to claim 2, whereinthe microcellular expanded composite material is microcellular expandedpolypropylene or microcellular expanded nylon.
 4. The battery packaccording to claim 1, wherein there are two side beams, which areconnected to two side walls of the frame respectively in a lengthdirection of the frame.
 5. The battery pack according to claim 1,wherein the interior of the side beam is filled with an energy-absorbingmaterial.
 6. The battery pack according to claim 5, wherein the interiorof the side beam is formed with a plurality of rib plates, which dividethe interior of the side beam into a plurality of installation chambersopening toward the frame, and the energy-absorbing material is filled inthe plurality of installation chambers.
 7. The battery pack according toclaim 5, wherein the energy-absorbing material is expanded polypropyleneor ethylene-vinyl acetate copolymer.
 8. The battery pack according toclaim 1, wherein the outer side wall of the frame is provided with a lugfor connecting to a vehicle, the interior of the side beam is formedwith an enveloping chamber opening toward the frame, and the lug isaccommodated in the enveloping chamber in a connected state.
 9. Thebattery pack according to claim 1, wherein the outer side wall of theframe is formed with a plurality of reinforcing ribs, a plurality offilling spaces are formed between the plurality of reinforcing ribs, andeach of the filling space is filled with a second thermal insulationmaterial.
 10. The battery pack according to claim 9, wherein the secondthermal insulation material is an expanded thermal insulation material.11. The battery pack according to claim 10, wherein the expanded thermalinsulation material is silicone foam, polyurethane sponge or polyvinylchloride expanded plastic.
 12. The battery pack according to claim 1,wherein the frame is a hollow structure and is formed with a cavity, andthe cavity is filled with a phase-change material.
 13. The battery packaccording to claim 12, wherein the phase-change material is an inorganicphase-change material, an organic phase-change material or a compositephase-change material.
 14. The battery pack according to claim 1,wherein the battery pack further comprises an active thermalcompensation assembly, which is provided on a heat dissipation path ofthe battery module and is configured to be able to heat the cells. 15.The battery pack according to claim 14, wherein the active thermalcompensation assembly is connected to a battery management system. 16.The battery pack according to claim 14, wherein the frame comprises anouter frame and an inner frame, the plurality of installation sites areformed in an enclosed manner between the outer frame and the innerframe, and the active thermal compensation assembly is provided on aninner side wall of the outer frame.
 17. The battery pack according toclaim 14, wherein the active thermal compensation assembly is anelectric heater, a graphene heat radiation sheet or a thermoelectriccooler.
 18. The battery pack according to claim 1, wherein the batterypack further comprises a temperature equalizing assembly, which isarranged in the frame and is configured to be able to balance thetemperature between different cells.
 19. The battery pack according toclaim 18, wherein the temperature equalizing assembly is attached to theouter side wall of the battery module close to an outer periphery of theframe.
 20. The battery pack according to claim 18, wherein thetemperature equalizing assembly is a heat pipe group, a thermalconductive aluminum plate group or a thermal conductive silicon padgroup.